1. Field of the Invention
The invention relates to an electric connector including a first housing of a male connector, and a second housing of a female connector into which the first housing is fit.
2. Description of the Related Art
An electric connector, such as a connector used for a glow plug igniting and/or pre-heating an engine and a connector connecting a combustion-pressure sensor and a wire harness to each other, generally includes a cylindrical male connector. Since the male connector is designed to be symmetrical in rotation relative to a female connector, the male connector can be fit into the female connector even if the male connector is rotated in any direction around an axis of the male connector. Thus, the male connector can be readily fit into the female connector even manually, even if those connectors are located at a place where an operator cannot see the connectors.
FIG. 15 illustrates the electric connector suggested in Japanese Patent Application Publication No. H9 (1997)-35825.
The illustrated electric connector includes a plug connector 1000 and a receptacle connector 1010. The plug connector 1000 includes a plug insulator 1001 having a rotation-symmetry shape, and a plurality of contacts 1002 each situated at different distances from a distal end of the plug insulator 1001. The receptacle connector 1010 is formed with a hole 1011 into which the plug connector 1000 can be inserted. When the receptacle connector 1010 is fit into the hole 1011, contacts 1012 face an inner surface of the hole 1011.
FIG. 16 is a cross-sectional view of the glow plug suggested in Japanese Patent Application Publication No. 2005-207730, and FIG. 17 is a perspective view of the glow plug.
The illustrated glow plug includes an electrically insulated casing 1100, sensor terminals 1101 to 1103 arranged outside and inside of the casing 1100, and a connector 1104. The sensor terminals 1101 to 1103 make electrical contact with sensor-connectors of a sensor (not illustrated) of a connector (not illustrated) when the glow plug is fit into the connector. The connector 1104 is electrically connected to a terminal of a heater of the glow plug when the glow plug is fit into the connector.
The conventional electric connectors illustrated in FIGS. 15 to 17 have an advantage that a male connector can be fit into a female connector even if the male connector is axially rotated in any direction. However, the conventional electric connectors are accompanied with a problem that if they are oscillated or they receive impact when a male connector is fit into a female connector, one of the connectors is forced to axially rotate, resulting in that the one of the connectors gradually retreats, and thus, the male connector might be released from the female connector. The male and female connectors may be formed with a projection and a recess into which the projection can be fit, respectively, in order to prevent the male and female connectors from axially rotating. However, if an intensive force acts on the male and female connectors in a direction of the axial rotation, the projection would be collapsed, resulting in that one of the male and female connectors makes relative axial rotation. Thus, the conventional electric connectors are accompanied with a problem of deterioration in reliability to electrical connection between the male and female connectors.